error/truncated aruments for renderers, refs #2130

datasette/renderer.py

@@ -27,7 +27,7 @@ def convert_specific_columns_to_json(rows, columns, json_cols):
     return new_rows
 
 
-def json_renderer(args, data, view_name, truncated=None):
+def json_renderer(args, data, error, truncated=None):
     """Render a response as JSON"""
     status_code = 200
 
@@ -47,8 +47,12 @@ def json_renderer(args, data, view_name, truncated=None):
     # Deal with the _shape option
     shape = args.get("_shape", "objects")
     # if there's an error, ignore the shape entirely
-    if data.get("error"):
+    data["ok"] = True
+    if error:
         shape = "objects"
+        status_code = 400
+        data["error"] = error
+        data["ok"] = False
 
     if truncated is not None:
         data["truncated"] = truncated
@@ -67,13 +71,13 @@ def json_renderer(args, data, view_name, truncated=None):
         if rows and columns:
             data["rows"] = [dict(zip(columns, row)) for row in rows]
         if shape == "object":
-            error = None
+            shape_error = None
             if "primary_keys" not in data:
-                error = "_shape=object is only available on tables"
+                shape_error = "_shape=object is only available on tables"
             else:
                 pks = data["primary_keys"]
                 if not pks:
-                    error = (
+                    shape_error = (
                         "_shape=object not available for tables with no primary keys"
                     )
                 else:
@@ -82,8 +86,8 @@ def json_renderer(args, data, view_name, truncated=None):
                         pk_string = path_from_row_pks(row, pks, not pks)
                         object_rows[pk_string] = row
                     data = object_rows
-            if error:
-                data = {"ok": False, "error": error}
+            if shape_error:
+                data = {"ok": False, "error": shape_error}
         elif shape == "array":
             data = data["rows"]
 

datasette/views/base.py

@@ -310,6 +310,7 @@ async def get(self, request):
                 request=request,
                 view_name=self.name,
                 truncated=False,  # TODO: support this
+                error=data.get("error"),
                 # These will be deprecated in Datasette 1.0:
                 args=request.args,
                 data=data,

datasette/views/database.py

@@ -360,7 +360,7 @@ async def query_view(
             message_is_html=True,
         )
     except sqlite3.DatabaseError as ex:
-        query_error = ex
+        query_error = str(ex)
         results = None
         rows = []
         columns = []
@@ -395,6 +395,7 @@ async def fetch_data_for_csv(request, _next=None):
             request=request,
             view_name="table",
             truncated=results.truncated if results else False,
+            error=query_error,
             # These will be deprecated in Datasette 1.0:
             args=request.args,
             data={"rows": rows, "columns": columns},

datasette/views/table.py

@@ -834,6 +834,7 @@ async def fetch_data(request, _next=None):
             request=request,
             view_name="table",
             truncated=False,
+            error=None,
             # These will be deprecated in Datasette 1.0:
             args=request.args,
             data=data,

docs/plugin_hooks.rst

@@ -516,6 +516,12 @@ When a request is received, the ``"render"`` callback function is called with ze
 ``request`` - :ref:`internals_request`
     The current HTTP request.
 
+``error`` - string or None
+    If an error occurred this string will contain the error message.
+
+``truncated`` - bool or None
+    If the query response was truncated - for example a SQL query returning more than 1,000 results where pagination is not available - this will be ``True``.
+
 ``view_name`` - string
     The name of the current view being called. ``index``, ``database``, ``table``, and ``row`` are the most important ones.